The invention concerns a metallic composite material for a sliding bearing comprising a metallic support layer, in particular of steel, and a bearing metal layer on a copper-tin basis with 2-6 weight % of tin. Composite materials for a sliding bearing of this type are used for manufacturing sliding bearing elements, in particular, sliding bearing shells and sliding bearing bushings for applications in or close to the motor. Typical applications of the type referred to herein are main bearing shells and connecting rod bearing shells. Connecting rod bearing bushings for bearing a piston pin in combustion engines are, in contrast thereto, often designed in the form of monometal bushings.
There are conventional composite materials for a sliding bearing comprising a bearing metal layer of CuSn4, in particular CuSn4Pb and CuSn5Zn. There are also conventional alloys on the basis of copper-tin, wherein intermetallic SnNi phases are formed by adding nickel. Bearing metals, which are designed for percussive or impact loads that typically occur in piston pin bushings, can be produced by so-called spinodal hardening. In this connection, high tin contents and high nickel contents are typically used, in particular, in the form of the alloys CuSn9Ni15 or CuSn6Ni6.
DE 10 2006 019 826 B3 discloses composite materials for a sliding bearing of this type with wide limits for nickel and tin, namely 1.0 to 15 weight % and 2.0 to 12.0 weight % of tin. However, the embodiments disclose high in and nickel portions of 5.2 to 5.6 weight % of tin and 5.6 to 6.0 weight % of nickel in order to obtain spinodal hardening. By means of heat treatment at 300 to 500° C. one obtains hardnesses of the bearing metal layer of presumably more than 170 HBW 1/30/10.
AT 509 459 discloses a copper-based anti-fretting layer on a side of the composite material for a sliding bearing opposite to the bearing metal layer and facing a housing. The total portion of the alloy components germanium, tin, indium, zinc, nickel, cobalt, bismuth, lead, silver, antimony as well as impurities caused by production is 1-30 weight %. The anti-fretting layer may comprise, in particular, 5-25 weight % of tin and 0.2 to 8 weight % of nickel.
It is the underlying purpose of the present invention to further develop a metallic composite material for a sliding bearing of the above-described type in such a fashion that its tribological properties are improved towards adaptability and particle compatibility even at high sliding speeds. A high breaking elongation shall be realized.